Planociraph co



A. E. LUNDELL.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR. 24. I917- Patenced Aug. 5, 1919.

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THE COLUMBIA PLANUGRAPH cu. WASHINGTON. IL c.

A. E. LUNDELL.

TELEPHONE EXCHANGE S-YSTEM. APPLICATION FILED MAR. 24. I911- 1,312,126, Patented Aug. 5,1919.

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APPLICATION FILED MAR. 24, I917.

Patented Aug. 5, 1919.

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APPLICA HON FILED MAR- 24,1911- L312J26 Patente Aug. 5,1919.

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A. E. LUNDELL.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED MAR. 24.1917. 1312 12 Patented Aug. 5,1919.

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A. E. LUNDELL. TELEPHbNE EXCHANGE SYSTEM.

APPLICATION FILED MAR. 24. 1917.

Patented Aug. 5, 1919.

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& T 2m m mum srnrns PATENT FF ALBEN E. LUN' DELL, OF NEW YORK, N. Y.,ASSIG1\TOR T WESTERN ELECTRIC COMPAIZF'SZ",

INCORPORATED, OF EW YORK, N. Y., A CORPORATION OF NEW YORK; i g p TELEPHONE-EXCHA GE sr srniu".

To all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Telephone EX- change Systems, of which the following is a Y full, clear, concise, and eXact description.

' switches and only a single keyboard,

This invention relates to telephone exchange systems and particularly to improvements in listening-key arrangements for semi-automatic telephone exchanges.

In its preferred embodiment the invention is applied to a semi-automatic telephone eX- change system in which an operators keyboard may be connected by selectively operable means to any one of a plurality of senders arranged to control the setting of selector switches. Such systems as disclosed and claimed in my copending application, Serial No. 139,511, filed December 29, 1906, comprise a listening key sequence switch having contacts through which the above mentioned connection between the keyboard and the sender may be-established. In view of the fact that each operators position'is equipped with a plurality of listening-key it is necessary to provide means whereby after the interconnection of the keyboard and a sender through the contacts of one listening key switch has been effected, the connection of this keyboard to another sender through contacts of another listening-key switch. is prevented until the keys have performed their controlling function.

In order to permit the operator to receive a call While one of her listening-key sequence switches is in the listening-in position,the present invention contemplates the provision of means whereby a listening key sequence switch may be moved first into a listening in position in which the keyboard is not connectedto a sender, and then into a second listening-in position, in which the keyboard is connected to the sender provided that no otherlistening key switch is standing in the second listeninginposition. As long as a listening key switch 13 standing in the second listening-in position, another switch is prevented from moving into that position.

It will be obvious to those skilled in the art that the use of the present invention is not limited to the particulartype of switching and controlling .devices disclosed, but is equally well applicable to manual telephone systems, and to systems in which other means than the one disclosed are used for connecting an operators set to a connecting circu t. y y y l 1 Figures 1 to 8 of the drawings taken to- Specification of Letters Patent. P t t d Ajjg,5,1919, Application filed March 24., 1917. Serial no. 157,100. 5

gether illustrate diagrammatica ly as much of a semi-mechanical telephone exchange system as is necessary for an understanding of the present invention. The order in which the drawings should be considered is indicated inFig. 9.

The reference numbers are used in such a manner that the hundreds digits was numbers used in a figure correspond to the number of the figure. For the sake of convenience, the name used in the description for designating certain switching devices is displayed in the drawings adjacent to the showing of such devices. SN and MGdesignate sensitive and marginal relays, and H and L, high and low wound resistances, respectively. 3

SeZector switches.

Theselectorswitches used in this system are of the so-called power-driven panel type described in Patent No. 1,123,696 to ELB. Craft and J N. Reynolds. For the purpose of distinguishing the various selector switches from each other, they willbe hereinafter referred to in the following manner: District selector (Fig. 1), cordfinder(Fig. 5),and sender selector (Fig. 5).: Each of these selector switches has a vertically 1novable brush rod carrying brushes arranged to wipe over a commutator plate, and thus control the operation of the respective selector switches, and wipers arranged to engage contacts of a terminal bank, bymeans of which connections may be established. Withthe exception of the sender selector, which carries only one set of wipers, all the selectors referred to carry five sets of wipers, only one set of wipers being shown in the drawings. The terminal bank of the districtselector and ofthe cord finder, comprises 500 rows of terminals divided into five sections, each the wiper sets may be trlpped to move its wipers intothe path of the terminals of its respective section. 1 The tripping device of the district selector and cord finder is of the same type as described in 7 Patent No. 1,177,044: to J. L. McQuarrie.

The brush rod of the sender selector carries a single set of wipers which are always in a'tripped position and rest normally on the lowermost row of terminals of a terminal bank. The wipers of the district selector are tripped only when they are moved out of normal, but before they reach the lowermost terminals of their respective terminal sections.

. Sequence switches.

The sequence switches shown in this system areof the type described in Patent No. 1,127,808. Sequence switch 108 controls, by means of its contacts, the circuits of the districtselector. All the sequence switch 0011' tacts shown in Fig. 1 are controlled by the sequence switch 108. In Fig. 2, two sequence switches 202 and 210 are indicated. Sequence switch 202 is the listening key sequence switch and controls, with certain exceptions to be noted later, all the contacts shown below the horizontal dotted line in Fig. 2, and sequence switch 210 is the keycontrol sequence switch controlling the contacts shown above the dottedline in this figure. Sequence switch 516 (Fig. 5) controls the circuits of the cord finder and the sender. selector. 'All the sequence switch contacts shown in this figure, with the exception of those within the dotted rectangle, are controlled by this sequence'switch. The latter mentioned contacts are controlled by an allotter 583 of the sequence switch type. Sequence switches 013 and 600 (Fig. 6) control, by means of their contacts shown to the left and right of the vertical dotted line of this figure, the circuits of a sender, and

- the circuits of a plurality of registers, re-

spectively. The sequence switch contacts shown in Fig. 7 are controlled by sequence switch 7 06. This sequence switch will be referred to asa class register controller.

Keg board.

The operators keyboard is shown in Figs. a key is depressed, it is locked by mechanical means, which may be released in response to the energization of a magnet 842, one being provided for each row of keys. There are nine rows of keys referred to as the office, tandem hundreds, tandem tens, tandem units, thousands, hundreds, tens, units and stations keys. Each row, with the exception of the ofiice and stations keys, comprises keys munbered 0 to 9, each key controlling as many contacts as is necessary for controlling the selectors and registers. The number of oilice keys depends on the trafiic requirements. The office keys are the equivalents of the tandem hundreds, tandem tens and tandem units. keys; that is to say, the depression of one office key results in the same combination of impulses as the depression of a certain combination of tandem hundreds, tens and units keys. One ofiice key is provided for controlling the seizure of a trunk leading to an important oliice, where as other offices may be reached by depressing a prescribed combination of tandem keys.

Registers.

Figs. 7 and 8 represent ten regilsters. These registers will be referred to as: 1, district group or tandem tens; 2, ofiice brush; 3, oflice group or tandem units; 4-, class; 5, incoming brush; 6, incoming group; 7, final brush; 8, final tens; 9, final units; and 10, stations registers. lVith the exception of the class and incoming group registers, each register comprises three rclays, two of the relays being of a marginal character and one of the relays sensitive. The incoming group register comprises one sensitive and one marginal relay, and the class register, two sensitive and three marginal relays. Each of the register relays is provided with a locking winding, and depending on the combination in which the relays of a certain register are actuated, the operation of the sender is determined.

Sender.

The sender (Fig. 6) comprises av pair of wipers 685 and 636 arranged to be moved step by step over a circle of terminals in the direction indicated by the arrow, in response to each complete operation (energization and deenergization) of a magnet 634. The terminals are divided into four sections A, B, C and D. The terminals of sections A and B are connected to conductors G57 and (342, respectively. The five terminals of sections C and D are numbered 0 to l, and the terminals of these two sections designated by the same numerals are connected in multiple. The two terminals numbered 0 are interconnected by means of sequence switch springs 66 1 and 665 in certain positions of sequence switches 600 and 613. Magnet 63lmay be energized and deenergized under the control of a stepping relay 632. A relay 633 controls the stopping of the sender wipers in a certain position determined by the setting of the various registers. The numerals appearing in the circles at the contacts of the various register relays indicate the ter minal of the sender to which those contacts are connected.

Detailed description. A subscriber at substation 100 (Fig. 1),

desiring to obtain a connection removes his receiver from the switchhook, whereupon a line relay LR. becomes energized and causes the lighting of a calling lamp CL. An operator, whose head set is indicated at 200, inserts thereupon a plug 101 into an answering jack 102 in which the calling subscribers line terminates. A circuit is closed thereupon from grounded battery, through the winding of a cut-ofl' relay CO, the sleeve contacts of jack 102 and plug 101 and the winding 01": relay 103 to ground, and another circuit from the plus pole of battery, through the primary winding of a repeating coil 104, the winding of an an swering supervisory relay SR, the lower limb of cord circuit 105, the ring contacts of plug 101 and jack 102, the calling substation 100, the tip contacts of jack 102 and plug 101,

.the upper limb of cord circuit 105 and the primary winding of repeating coil 104 to the minus pole of battery. Relays CO, 103 and SR become energized. The relay CO disconnects relay LR, whereuponlamp CL becomes extinguished.

Relay 103 closes a circuit from ground through its armature and front contact, conductor 106, the lower right-hand contact of sequence switch spring 201, and the power magnet of sequence switch 202 to grounded battery. Under the control of its normal contact 203, the sequence switch'200 i s moved out of position 1 and into position 7.

Each operators position is equipped with one telephone set 200, a relay 280, and a relay 281. For each cord like 105, one listening key sequence switch like 202 is provided, and by means of any of these listening key sequence switches, the telephone set 200 may be connected to a calling line through a cord circuit. The circuits of all the listening key sequence switches are like those of switch 202.

As soon as the sequence switch 202 reaches position 7, a circuit is closed from ground through the lower contact of sequence switch spring 283 and the winding of the relay 281 to grounded battery. The relay 281 becomes energized and prevents the connection of the operators telephone set 200 by means of another listening key sequence switch to another calling line in position 8 of said other listening key sequence switch. The operators telephone set 200 is connected through sequence switch contacts 204: and 205 to the cord circuit 105 tit and thus the operator is enabled to converse with the calling subscriber. A circuit is also closed from ground through the armature and front contact of relay 103, conductor 100, sequence switch contact 206, a conductor 207, the upper right-hand contact 01. sequence switch spring 107, and the power magnet of sequence switch 108 to grounded battery. The sequence switch. 108 is moved out 01' position 1 and under the control of its normal contact 109 into position 2.

If the operator is not listening in through another cord then all the sequence switches, except 202, are in the normal position 1 or in the listening-out position 12. In these positions of the other sequence switches, the contacts of sequence switch springs corresponding to 283, such as 283 are open and thus the relays 280 and 281 cannot be energized under the control of the other listening key sequence switches. Relay 280 being deenergized, a circuit is closed from ground through the armature and back contact of this relay. the upper contact of sequence switch spring 282, and the powermagnet of sequence switch. 202 to grounded battery, for driving this sequence switch out of position 7 and into position 8. As soon as the sequence switch 202 reached position 7, a circuit was closed from ground, through sequence switch contact 208, contact 209 of sequence 210, and the winding of a relay 211 to grounded battery. The relay 211 becomes energized and closes a. locking circuit for itself through its rightdiand front contact and armature and sequence swtich contact 208. The relay 281 being new deencrgized. the operators telephone set is connected to the cord circuit 105 through the armatures and contacts of relay 281 and the upper contacts of sequence switch springs 204; and 205. In position 8 of the sequence switch 202, the upper contact of sequence switch spring283 is closed, whereupon the relay 280 becomes energized and prevents the movement of: another listening key sequence switch out of position 7. i From the above description it will be obvious. that if another listening key sequence switch, such asthe one controlling the contact 283 is in position 7, then the relay 281 is energized and prevents the connection of the set 200 to the cord circuit 105 in position 8 of the sequence switch 202.

If the sequence switch controlling contact 283 is in position 8, the relay 280 is energized and prevents the movement of sequence switch 202 into position 8.

As indicated in Fig. 2 of the drawings, the relay 211 is common to a plurality of listening key switches and thus it may be energized also in response to the closure ofa sequence switch contact 208 controlled listening key by another listening-key sequence switch of the operator.

Setting of the rd finder and the sender selector.

Assuming that several cord circuits are 7 simultaneously taken into use by various operators, and thus several sequence switches like 108 are in position 2, a circuit is closed from ground, through the lower right-hand contact of sequence switch spring 112, conductor 111 (Figs. 1, 2 and 5), the lower armature and back contact of a relay 500,

for this reason, the relay 503, which is marginal in operation, is operated. Relays 500 and 501, resistance 502 and the conductors shown in the lower left-hand corner of Fig. 5, are individual to the link circuits 105 of the operators position. Similar apparatus are individual to each of the other positions. Relay 503 closes a circuit from ground, through its armature and front contact, the armature and back contact of a relay 504, and the back contact and armature of a magnet 505 to grounded. battery. Magnet 505 interrupt-s. its own circuit and thus causes, by means of a pawl 506 fixed to its armature, the stepping of wipers 507 and 508 mounted on a ratchet wheel 509. The wipers 507 and 508 are arranged to traverse terminals representing groups of linkcircuits. As soon as the wiper 508 engages terminal 510 individual to the group in which the link circuit 105 belongs, a circuit is closed from grounded battery, through the winding of relay 504, wiper 508, terminal 510, the lower back contact and armature of relay 501,the lower back contact and armature of relay 500, conductor 111 and sequence switch contact 110 to ground. Relay 504 becomes energized and opens in its back contact, the operating circuit of magnet 505, whereupon the wipers are arrested. Relay 504 closes also a circuit from ground, through the armature and front contact of relay 503, its armature and front contact, the armature and back contact of a relay 511, and the left-hand winding of a relay 512 .to grounded battery. Relay 512 closes a locking circuit for itself from ground, through its armature, front contact and right-handwinding, wiper 507, a terminal 513 individual to the group of cords 105, the lower winding of relay 501, and the windings of relays 511 and 514 to grounded battery. Relays 511,514 and 501 become energized. When relay 501 opens in its lower back contact the energizing circuit of relay 503, this relay is maintained energized by a circuit closed through the lower back contact of another relay 501 individual to another group of calling link circuits. Relay 504 becomes dei nergized. Relay 514 closes a circuit from ground through its armature and front contact, the upper left-hand contact of sequence switch spring 515, and the left-hand winding of a relay 517 to grounded battery. As will be hereinafter set forth, only one sequence switch like 516 is in position 1 at a time, and for this reason the energization of relay 514 results in the energization of only one relay like 517.

Upon the energization of relay 501 a circuit is closed from ground, through the lower right-hand contact of sequence switch spring 112, conductor 111, the lower armature and back contact and the lower armature and front contact of relays 500 and 501 respectively, and the winding of a trip magnet 541 to grounded battery. The trip magnet 541, by attracting its arn'iature, moves a trip finger 542 into the path of a catch 543 carried by cam 535. The connection of ground to the lower front contact of relay 501 results also in the shunting out of relay 512 which thereupon becomes deiinergized. Before the wipers of set 533 engage the lowermost terminals of bank 534 as will be hereinafter set forth, the trip finger actuates catch 543, causing thus cam 535 to be removed from between the wipers; whereupon these wipers are permitted to move in alinement with the terminals of the bank.

Upon the denergization of relay 504, relay 503 causes magnet 505 to move the wipers 507 and 508 away from terminals 513 and 510. Relay 504 breaks the circuit of magnet 505 in the same manner as above described when wiper 508 finds the terminal individual to the group containing the next calling link circuit.

The wipers of the sender selector 518 are normally resting on a set of contacts in which conductors leading to a sender terminate. Supposing that this sender is busy, as will be hereinafter set forth, ground is connected to terminal 519. For this reason a locking circuit is closed for relay 517, through wiper 520 of the sender selector 518, and the right-hand armature, front contact and winding of the relay 517 Upon the energization of relay 517, a circuit is closed from ground, through the left-hand armature and front contact of this relay, the upper right-hand contact of sequence switch spring 521 and the winding of a relay 522 to grounded battery. Relay 522 closes a circuit from ground, through its righthand armauture and front contact, the lower left-hand contact of sequence switch spring 523 and the power magnet of sequence switch 516 to grounded battery. The sequence switch 516 is thereupon moved out of position 1, and under the control of its normal spring 524, into position 2. A die cuit is now closed from grounded battery, through the winding of a magnet 525, the upper contacts of sequence switch spring 526 and the right-hand" front contact and armature of relay 522 to ground, and another circuit from. ground, through the lefthand armature and front contact of relay 517, the upper left-hand and lower righthand contacts of sequence switch spring 527, and the winding of a magnet 529 to grounded battery. Magnets 525 and 529 be come energized. By attracting its armature magnet 525 pressed brush rod 530 of cord finder 531 against a roller 532 constantly rotating in the direction indicated by the arrow. The brush rod 530 carries a plurality of sets of wipers similar to 533. These wipers are, arranged to enga e the sections of the terminal bank 534 comprising sets of terminals representin cord circuits such as 105, butthe wipers of each set are nor-, mally held apart by means of a cam like 535. A brush 536, arranged to engage various segments of a commutator plate, is also carried by brush rod 530. As soon as the brush rod has been moved in an upward dii'ection far enough to permit brush 536 to engage conducting segment 537, which happens prior to the engagement by the wipers of the lowest row of terminals of the re spective bank section, a circuit is closed from ground, through brush 536, conducting plate 537, the right-hand contacts of sequence switch spring 560, the upper front contact and armature of relay 501, and the winding of relay 500 to grounded battery. The relay 500 becomes energized and closes a locking circuit for itself through conductor 111 and sequence switch spring 112, to ground, whereupon relays 501, 511 and 514 become denergized. Relay 514 closes a circuit from ground, through its armature and back contact, the upper right-hand contact of sequence switch spring 523, and the power magnet of sequence switch 516, to grounded battery, whereupon the sequence switch is moved out of position 2 and into position 3. Relay 511 being deenergized, the relay 512 is permitted to operate under the control of the next calling cord circuit.

"When the sequence switch 516 moved out of position 2, relay 522 was maintained energized by a circuit extending from ground, through its winding, the upper lefthand contact of sequence switch spring 521, and the right-hand back contact and armature of a test relay 545 to ground. As soon as the wipers 533 engage the set of terminals representing cord 105, a circuit is closed from ground, through the upper right-hand contact of sequence switch spring 112, a con- &

ductor 186, a resistance 212, conductor 213, terminal 546, wiper 547, the lower righthand contact of sequence switch spring 547 and the windings of relay 545 to grounded battery. If full batterypotential exists on terminal 546; that is to say, if no other cord finder engages with its test wiper this terminal, then relay 545, which is marginal in operation, becomes energized and closes a locking circuit for itself through its lefthand armature and front contact, and conductor 213. By short-circuiting its high resistance left-hand. winding, this relay decreases the potential on terminal 546, so as to prevent the ener ization of a test relay associated with another cord finder, when such cord finder tests the terminals representing cord 105. As a precautionary measure, other means are provided in the right-hand armature and front contact of relay'545, and a resistance 548, for decreasing the potential on test terminal 546 in position 2 to 2%- of sequence switch 516.

By opening its right-hand back contact, relay 545 opens the circuit of relay 522. This relay, however, remains energized, ground being connected to its winding through brush 536 as long as this brush rests on a conducting plate 549. As soon, however, as the brush 536 engages one of the insulated segments 550, which indicates that the wipers 533 are centered on the se lected set of terminals, the relay 522 becomes denergized and closes a circuit from ground, through its right-hand armature 0 and back contact, the upper left-handcontact of sequence switch spring 523, and the power magnet of sequence switch 516 to grounded battery, for driving this sequence switch out of position 3 into position 4. As soon as relay 522 becomes denergized, the circuit of magnet 525 is opened, and thus the brush rod 530 is arrested with the wipers 533 in engagement with the selected set of terminals.

Inposition 4 of sequence switch 516, a circuit is closed from ground, through the contact of sequence switch spring 580, the upper left-hand contact of spring 581 and the power magnet of allotter 583, to grounded battery. The allotter, is moved out of position 1 and under the control of its normal contact 584 into position 2. The allotter closes now the contact of its spring 582 and causes the preselection of a cord finder and 120,

a sender selector switch by moving their associated sequence switch out of position 18 into position 1, as will be hereinafter set forth in connection with sequence switch 516.

The magnet 529, by attracting its armature, presses brush rod 552 against a roller 553, constantly rotating in the direction indicated by the arrow. The brush rod 552 of sender selector 518 carries a set of wipers 554 and a brush 555. The energizing circuit of "switch spring 527, brush 555,

magnet 529 will be maintained closed while relay 517 is energized, and the upper lefthand and lower right-hand contacts of sequence switch spring 527 are closed. For this reason the wipers 554 continue to move in an upward direction until wiper 520 engages a terminal 551 individual to a sender, the sequence switch 600 of which is in posi tion 1, and maintains the upper contacts of its spring 601 open, and which sender is not occupied byanother sender selector. The relay 517 although its above traced locking circuit is open, is then maintained energized by a circuit extending from ground, through its left-hand armature and front contact, the upper lefthand contact of sequence conducting plate 556, the upper right-hand contact of sequence switch spring 515, and the lefthand winding of relay 517 to grounded battery, as longas brush 555 engages the conducting segment 556. When,,however, the brush 555 engages an insulated segment 558, indicating thus that the wipers 554 are centeredvon the selected set of. terminals, relay 517 becomes denergized, opens the circuit of magnet 529 and closes a circuit from ground, through its left-hand armature and back contact, the lower right-hand contact of sequence switch spring 523, and the power magnet of sequence switch 516 to grounded battery, for moving this sequence switch out of position 4 and into position 15.

It may be seen from the above that if a plurality of sequence switches like 108 are moved into position 2 at the same time, then, under the control of the devices and circuits represented in the lower part of Fig. 5, one call is taken care of and the setting of an other pair of cord finderand sender selector switches is delayed until the wipers 533 of cord finder 531 are tripped, i. 0., until the five sets of wipers carried by brush rod 530,

have been moved a sufficient distance so as to prevent the tripping of another set of brushes of this cord finder in response to the energization of another trip magnet, such as 541*.

If only a single sequence switch like 108 is moved into position 2, it is not necessary to operate the above described barring means. Due to the marginal character of relay 503, it will not operate in response to current flowing through a circuit which contains only one resistance like 502. A circuit will therefore be closed from ground, through the back contact of relay 503, the'left-hand armature and back contact of relay 511, the upper winding of the relay 501 individual to a group of cord circuits 105, the upper back: contact and armature of relay 500, conductor 535, and the contact of se quence switch spring 110 to grounded batter Relay 501 becomes energized and closes a circuit fromgrounded battery,

through the windings of relays 514 and 511, the lower winding, front contact and armature of relay 501, the lower back contact and armature of relay 500, conductor 111, and the lower right-hand contact of sequence switch spring 112, to ground. A branch of this circuit extends from grounded battery, through the winding of trip magnet 541 to the lower front contact and armature of relay 501. The relays 514 and 511 and the magnet 541 become energized and the switches 51S and 531 are operated in the same manner as above described.

Upon the setting of cord finder 531 and sender selector 518, the sequence switches are in the following positions: sequence switch 108 in position 2, sequence switch 202 in position 8, sequence switch 516 in position 15, and all he other sequence switches in position 1.

Adjustment of the keyboard.

Supposing that the called subscribers number is 13-9876, the operator depresses the B oilice key, the number 9, 8, 7, 6 thousands, hundreds, tens and units keys and a start key 404, respectively, whereupon the keys remain locked in their depressed position.

In response to the depression of ofiice key B, contacts 353, 354, 355 and 356 of this key are' closed. The closure of these contacts results in the establishment of the following circuits:

1. From grounded battery, through the winding of a relay 349, contact 353, conductor 357 (Figs. 3, 2 and 1), the winding of a relay 113,, to ground. Relays 113 and 349 become energized.

2. From ground, through the winding of a relay 214, a conductor 215, the winding of relay 303, contact 354, and the winding of a relay 305, to grounded battery. Relays 214, 303 and 305 become energized.

3. From grounded battery, through a resistance 35S, conductor 359, key contact 355,

conductor 360, the winding of relay 311, conductor 312, conductor 215, and the winding of relay 214 to ground. Relay 311 becomes energized.

4. From grounded battery, through the winding of a relay 344, conductor 361, key contact. 356, conductor 346, the right-hand winding of a relay 329, the winding of a relay 313, conductors 312 nd 215, and the winding of relay 214 to ground. Relays 344, 329 and 313 become energized.

In responseto the energization of relay 344, a circuit is closed from grounded battery through the power magnet of sequence switch 210, the upper lefthand contact of sequence switch spring 237, a conductor 26!, the left-hand front contact and armature of relay 344, a conductor 263, the left-hand inner front contact and armature of relay 211, a sequence switch contact 262, a conductor of a marginal 132, and the upper left-hand contact of sequence switch spring 112 to ground. The sequence switch 210 is moved out of position 1, and under the control of its normal contact 265 into position 2. As above stated only one listening key sequence switch can be in position 8 at a time and thus only one of these sequence switches can connect the keyboard to a set of registers through its contacts 224, 226 and 228.

Setting of the class register.

As soon as sequence switch 210 reaches position 1%,, a circuit is closed from grounded battery, through the relatively low resistance 319, the front contact and armature of relay 303, conductor 231, the lower righthand contacts of sequence switch springs 230 and 229, the upper contact of sequence switch spring 228, conductor 566, terminal 579, wiper 528, sequence switch contact 565, wiper 540, terminal 539, conductor 620, the upper right-hand contact of sequence switch spring 619,. conductor 710, and the left-hand windings of a marginal relay 7 04 and a sensitive relay 709, to ground. Due to the relatively low resistance of the circuit, both 1e lays become energized.

In position 1 of sequence switch 210, another circuit is closed from grounded battery, through the relatively low resistance 339, the front contact and armature of relay 349, a conductor 363, the upper contacts of sequence switch springs 266 and 226, co11 ductor 227, terminal 578, wiper 57 6, sequence switch contact 563, wiper 538,terminal 557, conductor 56-1, the right-hand contact of sequence switch spring 615, a conductor 616, and the left-hand windings relay 702 and a sensitive relay 703 to ground. Due to the relative low resistance of the circuit both relays 7 02 and 7 03 become energized.

When the sequence switch 210 reaches position 2, a circuit is closed from ground, through the upper armature and back contact of a relay 219, the low resistance lefthand winding of a relay 220, a, conductor 221, the front. contact and armature of relay 305, conductor 318, the lower right-hand contacts of sequence switch springs 222 and 223, the upper left-hand contact of sequence switch spring 224, conductor 225, terminal 577, wiper 575, the lefthand contacts of sequence switch spring 560, wiper 544, terminal 559, conductor 561, the upper contacts of sequence spring 603, conductor 604-, the lefthand winding ot' a marginal relay 7 00, conductor 701, the upper right-hand contact oi sequence switch spring 605, and the winding of a relay 606, to grounded battery. Re lays 220, 606, and, due to the relatively low resistance of the left-hand winding of relay 220, the 'marginal relay700, becomeenen gized.

Relay 606 closes a circuit from ground, through its armature and trout contact, the lower contacts of sequence switch spring 601, and the winding of a relay 608 to grounded battery. Relay 608 closes a circuit from ground, through its lower armature and front contact, the upper left-hand contact of sequence switch spring 609 and the power magnet of sequence switch 600 to grounded battery, for moving this sequence switch out of position 1; under the control 01 its master contact 668, the sequence switch 600 is moved into position 2. The relay 606 does not become deenergized upon the opening of the lower contacts of sequence switch spring 601, a locking circuit being closed from grounded battery, through the winding, and upper front contact and ari'i'iature of this relay, conductor 610, terminal 551, wiper 520, the right-hand armature and back contact of test relay 517, and the left-hand contact of sequence switch spring 562, to ground. A circuit is now closed from ground, through sequence switch contact 611, the left-hand contact of sequence switch spring 612 and the power magnet of sequence switch 613 to grounded battery. Se quence switch 613 is moved out of position 1 and under the control of its normal con tact 614 into position 2.

As soon as sequence switch 600 reaches position 2, a circuitis closed from grounded battery, through the upper contact of se quence switch spring 621, conductor 712, and then through the right-hand windings, armatures and front contacts of relays 700, 704:, 709, 7 02 and 703 in multiple, to ground. These relays remain thus locked up. Due to the fact that all the class-register relays are energized, the circuit which was prepared from ground through sequence switch contact 617, conductor 618 and any one of the sequence switch springs 739, 711, 708 and 7 10 for the. class-register sequence switch 706 and relay 705, will be maintained open in the outer back contacts of the class register relays. The sequence switch 706 remains thus in position 1 and the relay 705 does not become energized.

Normally a shunt is placed around the winding of relay 219, through the lower armature and back contact of this relay and the left-hand back contact of relay 220. As soon as relay 220 becomes energized and opens its left-ha11d back contact the relay 219 is permitted to become energized by current flowing from ground, through its winding, the left-hand contact of a sequence switch spring 218, and a resistance 217 to grounded battery. The ground that was supplied through the upper back contact of relay 219 is now supplied through the lefthand front contact of relay 220 for maintaining the latter energized.

As soon as sequence switch 600 reaches position 2, a circuit is closed from grounded battery, through the power magnet of sequence switch 600, thearmature and back contact of a relay 623, the left-hand contact of sequence switch spring 622, and the front contact and armature of relay 606 to ground.

The sequence switch 600 moves out of posi- Setting of the district group register.

When the sequence switches 210 and 600 reach position 2%, a circuit is prepared from ground through the left-hand windings of a margmal relay 718, and a sensitive relay 717, conductor 625, the upper lefta I hand contact of sequence switch spring 624,

conductor 561, terminal 559, wiper 544, the left-hand contacts of sequence switch spring 560, wiper 57 5, terminal 577, conductor 225, the upper lefthand contact of sequence switch spring 224, the right-hand contact of sequence switch spring 223, the upper righthand contact of sequence switch spring 222, and conductor 267. Due to the fact that neither of the relays 310 and 351 is energized, this circuit is not completed and therefore relays 718 and 717 remain deenergized.

When the sequence switches 210 and 600 reach position 3 a circuit is closed from grounded battery through the windings of a relay 623, the lower contact of sequence switch spring 627, conductor 720, the lefthand winding of a marginalrelay 719, conductor 626, conductor 620, terminal 539, wiper 540, the sequence switch contact 565, wiper 528,- terminal 579, conductor 566, the upper left-hand contact of sequence switch spring 228, the lower right-hand contact of sequence switch spring 229, the upper righthand contact'of sequence switch spring 230, conductor 321, the armature and front contact of the relay 311, conductor 320, conductor 331, the windings of relay 233, and the upper back contact and armature of relay 234 to ground. Relays 233 and 623 become energized. Due to the fact, however, that the left-hand winding of relay 233 is of a relatively high resistance, the relay 719 remains deenergized. Upon the energization of relay 233, a shunt is removed from around the winding of relay 234 in the same manner as was described in connection with relay 219, and this relay becomes energized by current flowing in the circuit extending from rounded battery through resistance 217, tie right-hand contact of sequence switch spring 218, and the winding of relay 234 to ground.

Relay 623 closes a circuit from ground through the armature and back contact of relay 606, the right-hand contacts of sequence switch spring 622, the front contact and armature of relay 623, and the power magnet of sequence switch 600 to grounded battery, for moving this sequence switch out of position 3 and into position 4. Upon the opening of the lower contact of sequence switch spring 627 the circuit of relays 623 and 233 is broken and the latter closes a circuit from ground through its armature and back contact, the lower armature and front contact of relay 234, the right-hand back contact and armature of relay 220, the upper left-hand contact of sequence switch spring 237, and the former magnet of se quence switch 210 to grounded battery, for moving sequence switch 210 out of position 3 and into position 4.

District translation.

When the sequence switches 210 and 600 move through position 3%}, a circuit is prepared from ground through the left-hand winding of relay 742, conductor 741, the lower right-hand contact of sequence switch spring 619, conductor 620, terminal 539, wiper 540, the sequence switch spring 565, wiper 528, terminal 579, conductor 566, the upper contact of sequence switch spring 228, the right-hand contact of sequence switch spring 229, the upper left-hand contact of sequence switch spring 230, conductor 325, and then, due to the fact that relay 306 has not been energized, this circuit will not be completed, and thus the relay 742 arranged to control the translation remains deenergized.

O/fice translation.

When the sequence switches 210 and 600 reach position 4, a circuit is closed from ground through the upper armature and back contact of relay 219, the left-hand winding of relay 220, conductor 221, conductor 323, the back contact and armature of relay 322, conductor 238, the upper lefthand contact of sequence switch spring the right-hand contact of sequence switch spring 223, the upper contact of sequence switch spring 224, conductor 225, terminal 577, wiper 575, the left-hand contacts of sequence switch spring 560, wiper 544, terminal 559, conductor 561, the upper contact of sequence switch spring 603, conductor 604, the left-hand winding of marginal relay Add,

new

721, conductor 628, the upper left-hand contact of sequence switch spring 605, and the winding of relay 606 to'grounded battery. Relays 606 and 220, due to therelativelylow resistance of the circuit relay 721, become tion 5, whereupon the upper left-hand con-h tact of sequence opened and relay tures recloses the switch spring 605 will be 220 byreleasing its armaout of position 4 and into position 5.

When the sequence switches 210 and 600 pass through position 3% a circuit is prepared from ground through the left-hand windings of a marginal relay 724 and a sensitive relay 725, conductor 726, the right-hand contact of sequence switch 624, conductor 561, terminal 559, wiper 544, left-hand contacts of sequence switch spring 560, wiper 575, terminal 577, conductor 225, the upper left-hand contact of sequence switch spring 224, the right-hand contact of sequence switch spring 223, the lower-lefthand contact of sequence switch spring 222, conductor 239, and then, due to the fact that neither of the relays 347 and 317 is energized, this circuit is not completed and relays 724 and 725 remain deenergized.

When the sequence switches reach posi is closed from ground through the upper armature and back contact of relay 234, the windings of relay 233, conductor 331, conductor 320,the back con tact and armature of relay 328, conductor tion 5, a clrcuit 240, the lower left-hand contact of sequence switch spring 230, the right-hand contact of sequence switch spring 229, the upper contact of sequence switch spring 228, conductor 566, terminal 579, wiper 528, sequence switch contact 565, wiper 540, terminal 539, 0011: ductor 620, conductor 626, the left-hand winding of a marginal relay 722, conductor 723, the upper contact of sequence switch spring 627, and the grounded battery.

come energized. Due to the fact, however, that the windings of relay 233 are of a relatively high resistance, the marginal relay 722 will not become energized. The relay 623 closes a circuit in the above described manner for drivmg the sequence switch 600 out of position 5 and into position 6. The

relay permits the energization erreiaiy above-traced circuits and causes the movement of sequence swltch 210 upper spring winding of relay 623 to; Relays 623 and 233 be- 234 and, upon the opening y of thecircuit by sequence switch 600, relay 233 causes the movement of sequence switch 210 out of position 5 and into position 6;

Setting of the ofitcc grouprcgistcr.

When the sequence switch 600 and se quence switch 210 move into position 5 circuit is closed from grounded battery through resistance front contact and armature of relay 329, conductor 242, the upper left-hand contact of sequenceswitch spring 241, the righth'and contact of sequence switch spring 229,

the upper contact 228, conductor 566, terminal579, wiper528, sequenceswitch contact565, wiper 540, terminal 539, conductor 620, the upper lefthand contact of sequence switch spring 619, conductor7l5, the left-hand windings of a sensitive relay 714, and a marginal relay 713 to ground. Due to the fact that the re sistance 319 is relatively low, both relays 714 and 713 become energizedand lock up through their right-hand armatures, front contacts, and windings, and conductor 716 in multiple with the other register relays.

When the sequence switches reach position 6 aflcircuit is closed from ground through the upper lay 219,the low resistance left-hand winding of relay 220, conductor 2 21, conductor of sequence switch spring 323, the front contactand armature of relay 3'13, conductor 244, the lower left-hand conhand contact of sequence switch spring223, the upper contact of sequence switch spring 224, conductor 225, terminal 577, wiper 575, the left-hand contact of sequence switch spring 560, wiper 544, terminal 559, conductor 561, the upper contact of sequence switch spring 603, conductor 604, the left-hand winding of a marginal relay 727; conductor 629, the lower left-handcontaot of sequence switch spring 605, and the windingof relay 606 to grounded battery. Due to the low resistance of the left-hand winding of relay 220, relays 727,606 and 220 become energized The relay 727 locks up through its right-hand winding, a multiple with 220 permits the energization of relay 219 and relay 606 causes the movement of sequence switch 600 out of position 6 and into position 7. Upon the opening of the lower left-hand contact of sequence switch spring 605, relay 2'20 becomes deenergized and recloses the above-traced circuit and drives the sequence switch 210 outqof position 6 and into position This sequence switch is driven ou'totposition 7 into position 8 by a circuit extending from grounded battery through the power magnet of the sequence switch, the upper right-hand contact of se- 319, conductor 324, the

armature and back contact of rearmature, front contact and relay 714. Relay 45 switch spring- 65-1, conductor 652, the, left- 7 7 (Figs. 2,6:

' .umn,

quence switch Spring: 23,7, cond ucton 405,;

and; 4L)-:and a contact 404 (closed in response'to: the-actuation of, anyone of the keys in the stations: row), to ground. Since the. startkey is. in the stations colthis circuit will be completed and sequence; switch 210; will; be waved into position, 8. I

Relay- 7 ,5 los ng cle ne gifzed a ci it i closed from ground, through the armature a and; bacl; contact of: this relay, conduc tor 7 28,

= que e the; upper right-hand contact of sequence witch; pr-ingfiQtbant-i the P magnet seq-11sec wit. 11 ,00 teem nded attery r mo-v' hisseq rence; switch out ofposition 7' udinto-po itinn 8-,. r

V Set-ting of the, incoming brush register.

v spring 2ii5,conductor-24c6, contact 4;02 of the No.6 thousands key-,conductor 326. and a relatively high, resistance 327 to grounded battery. Due, to. the high-resistance of the circuit, only: the sensitive relay S01 becomes energized, This relay closes a locking circuit. for itself from, ground through its inner trout, contact armature and right-hand winding, a, conductor 803, and the lower contact 0t sequenceswitch spring- 621- to ground- When the, two sequence switches reach. positiorr 8 a circuit. is closed from grounded battery, through the winding of relay 623, the lower left-hand contact oi sequence hand winding; of a marginal relay 804k, conductor 80,5, conductor 806', conductor 620, terminal 539, wiper 5&0, sequence switch contact 565, wiper 5'28, terminal 579, conductor 566,, the upper contact of sequence switchspring 228, the right-hand contact of:

quence switch spring 229, the upper. lefthand contact; of sequence switch spring 247, conductor 248, contact cos of the thousands 'key'No. 9,cconductor- 320, conductor 331, the

windings of relay 238- and the upper back contact and armature oi relay 234C toground; The relays 62% and becomeenergized. Dueto, the high resistance of the circuit, the relay; 8041 does not: become energized. RB- lay .233 opens the shuntaround the winding of relay 23 i; and thisrelay becomes energized, Relay 23, c uses the movement of sequence switch 600 out of position 8 into position 9, whereupon relay 233 becomes deenergized and moves sequence switch 210 out of position 8 into position 9 in the above described manner. Relay 234 becomes delinergized.

Setting of the incoming group register.

Then the sequence switches 210 and 600 reach position 8%}, a circuit is prepared from ground through the left-hand winding of a. sensitive relay 84:3, conductor 808, the lower left-hand contact of sequence switch spring 653., conductor S06, condnctor 620, terminal 539, wiper 5&0, the sequence switch contact 565, wiper 528, terminal 579, conductor 566, the upper contact-oi sequence switch spring 228, the righthand contact of sequence switch spring 22$), the upper rigl'it-hand contact of sequence switch spring 247, conductor 2&9, but in view of the fact that conductor 24-9 is not connected to any contact of the No. 9 thousands key, thisv circuit is not completed, and therefore relay 807 remains deenergized.

When the sequence, switches reach position 9 a circuit is closed from grounded battery, through the winding of relay 606, the upper left-hand contact of sequence switch spring 654, conductor 655, the left-hand winding, of-a marginal relay 809, conductor 81-0, the upper contact of sequence switch spring 608, conductor 561, terminal 559, wiper 544, the left-hand contacts of sequence switch spring 560, wiper 575, terminal 577, conductor 225, the upper contact of sequence switch spring 224, the right-hand contact oi sequence switch spring 223, the upper lefthand contact of sequence switch spring 2-H), conductor .250, contact 400 of the hundreds key No. 8, conductor 401, conductor 330, the windings of relay 220, and the upper back contact and armature of: relay 219, to ground. Relays 220 and 606 become energized, and the former permits relay 21K) to pull up its armature. Relay S09, however, due to the high resistance of the circuit does not hecome energized. Relay 606 closes a circuit including the left-hand contacts of sequence switch spring- 622, for driving sequence switch 600 out of position 9 and into position 10'. Relay 220 bccoincs then dciincrgized and closes a circuit through the righthand contact of sequence switch spring 232, for driving sequence switch 210 out .01 position 9' and into position 10.

Setting of the final'bruslz ism'.

When. the sequence switches reach position a circuit is. prepared from ground through the left-hand windings oi n'nnginal relay 811 and a sensitive relay 812, conductop 813, the lower, left-hand contact of quence switch spring 650, conductor 561,

terminal 559, wiper 544,the left-hand c011 tacts of sequence switch spring 560, wiper 575, terminal 577, conductor 225, the upper contact of sequence switch spring 224, the right-hand contact of sequence switch spring 223, the lower left-hand contact of sequence switch spring 245, and conductor 251, but then, in View of the fact that the hundreds key N o. 8 does notclose a contact including conductor 251, this circuit is not completed and relays 811 and 812 remain deenergized.

When the sequence switches reach position 10, a circuit is closed from grounded battery,

back contact and armature of relay 234 to ground. Relays 233 and 623 become energized, and the former causes the operation of relay 234. Due circuit, relay 814 becomes energized and locks up in the register relays. Relay 623 closes a circuit ineluding sequence switch spring 622, for driving sequence switch 600 out of position 10 and into position 11. Relays 233 and623 become then deenergized and the, former closes a circuit to drive the sequence switch 210 out of position 10 and into position 1].. Relay 234 becomes deenergized.

Setting of tits final tens register.

When the sequence switches reach position 10%, circuit is prepared from ground, through the left-hand windings of a marginal relay 815 and a sensitive relay 816, conductor 817, the upper right-hand contact of sequence switch spring 653, conductor 620, terminal 539, wiper 540, sequence switch contact 565, wiper 528, terminal 579, conductor 566, the upper left-hand contact of sequence switch spring 228, the right-hand" contact of sequence switch spring 229 the lower lefthand contact of sequence switch spring 247, and conductor 253, but then, in View of the fact that the No. 7 tens key does not have a contact through which this conductor 253 may be extended, the circuit is not completed and relays 815 and 816 remain deenergized.

When the sequence switches reach posi tion 11, circuit is closed from grounded battery, through the winding of relay 606, the

switch contact 565, wiper 528, conductor 566, the upper 0011-:

spring 229,

tothe low resistance of the same manner asthe other lower righthand contact 01 sequence switch spring 654, conductor 818, the left-hand winding of a marginal relay 8.19, conductor 810, the upper contact of sequence switch spring 603, conductor 561, terminal 559, wiper 544, left-hand contacts of sequence switch spring 560, wiper 575, terminal 577, conductor 225, the upper contact of sequence switch spring 224., the right hand contact of sequence switch spring 223, the upper right-hand contact of sequence switch spring 215, conductor 332, contact 408 of the tens key No. 7, conductor 401, conductor 330, the windings of relay 220 in series and theupper back contact and armature of relay 219 to ground. Relays 220 aiid606 be come energized, but, due to the high is sistan ce of the circuit, relay 819 does notbecome energized. Relay 220 permits the energization of relay 219. Relay 606 closes a circuit including sequence switch spring 622 for driving quence switch 600 out of position 11 and into position 12, whereupon relays 220 and 606 become deenergized, and the former moves the sequence switch 210 out of position 11 and into position 12 by acircuit including the upper right-hand contact of sequence switch spring 232. Relay 219 becomes deenergized.

Final tens translation.

When the sequence switches 600 and 210 reach position 112-, a circuit is prepared from ground, through the right-hand windingo'f arelay 832, a conductor 833, the lower coutact of sequence switch spring 603, conductor 561, terminal 559, Wiper 544,- the lefthand contacts of sequence switch spring 560, wiper 575-, terminal 577, conductor 225, the uppercontact of sequence switch spring 224, the right-hand contactoit sequence switch spring 223, the upper left-hand contact of sequence switchspring 243, and condiutor 336, contact 418 of the No. 7 tens key, ronductor 324 and the low resistance 319 to gi.'oun iled battery The relay 832 becomes energized, and locks upin the same manner as the reg ister relays. i

Final units translation,

When the sequence switches reach position 12, a circuit 15 closed from grounded batt through the winding of relay 623, the upper right'hand contact of sequence switch sprin.. 651, conductor 820', the lefthand winding of a marginal relay 821, conductor 806, conductor 620, terminal 539, wiper 540, sequence switch contact 565, wiper 528, terminal 57 9, conductor 566, the upper contact of sequence switch spring 228, the right-hand contact o:l:' sequence switch spring 229, the lower righthand contact of sequence switch spring 241, conductor 333, contact 409 of units key 1 0. 6, conductor 407, conductor 235, the low rethe left-hand contacts of sistance right-hand winding of relay 233 and the upper back contact and armature of relay 234, to ground. Relays 233 and 623 become energized and the former permits relay 234 to operate. Due to the low resistance of the circuit, relay 821 also becomes energized and locks up in the same manner as the other register relays. Relay 623 closes a circuit including the right-hand contacts of sequence switch spring 622, for driving sequence switch 600 out of position 12 and into position 13. Relays 623 and 233 become then deenergized and the latter closes a circuit to move the sequence switch 210 out of position 12 and into position 13'.

r 7 Setting of the final am'ts register.

When the sequence switches reach position 12?; a circuit is closed from ground, through the left-hand windings of a marginal relay 822 and a sensitive relay 823, conductor 824,

the lower right-hand contact of sequence switch spring 653, conductor 620, terminal 539', wiper 540, sequence switch contact 565, wiper 528, terminal 579, conductor 566, the upper contact of sequence switch spring 228,

the right-hand contact of sequence switch I nal 577,

spring 229, the upper right-hand contact of sequence switch spring 241, conductor 254, contact 410 of the No. 6 units key, conductor 324, and the low resistance 319' to grounded battery. Due to the low resistance of the circuit, both relays 822 and 823 become energized and lock up through their right-hand windings and conductor 803.

When the sequence switches reach. position 13, a circuit is closed from grounded battery, through the winding of relay 606, the lower switch spring 654, conductor 825, the lefthand winding of a marginal relay 826, conductor 810, the upper contact of sequence switch spring 603, conductor 561, terminal 559, wiper 544, the left-hand contacts of sequence switch spring 560, wiper 57 5,. termiconductor 225, the upper contact of sequence switch spring 224, the right-hand contact of sequence switch spring 223, the upper right-hand contact of sequence switch spring 243, conductor 255, contact 411 of units key No. 6, conductor 323, conductor 221, the left-hand winding of relay 220 and the upper back contact and armature of relay 219 to ground. Relays 220 and 606 become energized and the former causes the operation of relay 219. Due to the low reslstance of the circuit, relay 826 becomes energized and locks up. Relay 606 closes a circuit including the left-hand contacts of sequence switch spring 622, for driving sequence switch 600 out of position 13 and into position 14, whereupon relays 606, and 220 become denergized and the latter moves left-hand contact of sequence,

the sequence switch 210 out of position 13 and into position 14. Relay 219 becomes then deenergized.

Setting of the stations register.

Vhen the sequence switches reach position 13%, a circuit is closed from ground, through the left-hand windings of a marginal relay 827, and a sensitive relay 828, conductor 829, the upper right-hand contact of sequence switch spring 650, conductor 561, terminal 559, wiper 544, the left-hand contacts of sequence switch spring 560, wiper 575, terminal 577, conductor 225, the upper contact of sequence switch spring 224-, the right-hand contact of sequence switch spring 223, the lower right-hand contact of sequence switch spring 243, conductor 334, contact 416 of the start key 414, conductor 338, and the low resistance 339 to grounded battery. Due to the low resistance of this circuit both relays 827 and 828 become energized and lock up through their right-hand windings and conductor 803.

When the sequence switches reach position 14, a circuit, is closed from grounded battery, through the winding of relay 623, the lower right-hand contact of sequence switch spring 651, conductor 830, the lefthand winding of marginal relay 831, conductor 805, conductor 806, conductor 620, terminal 539, wiper 540, sequence switch contact 565, wiper 528, terminal 579, conductor 566, the upper contact of sequence switch spring 228, the right-hand contact oi sequence switch spring 229, the lower lefthand contact of sequence switch spring 241, conductor 335, contact 415 of the start key 414, conductor 320, conductor 331, the windings of relay 233 and. the upper back contact and armature of relay 234 to ground. Relays 233 and 623 become energized, but due to the high resistance of the circuit relay 83 1 is not energized. Relay 233 permits relay 234 to pull up its armatures. Relay 623 closes a circuit including the righthand contacts of sequence switch springs 622, for driving sequence switch 600 out of position 14 and into position 15, whereupon relay 233 becomes deenergized and causes the movement of sequence switch 210 out of position 14 and into position 15.

Restoration of the keyboard and its eontroh Zing apparatus. 

